#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>


#define BUF_SIZE 1024
void error_handling(char *msg);

int main(int argc, char *argv[])
{
    int serv_sock;
    int clnt_sock;
    int str_len;
    int i;

    struct sockaddr_in serv_adr;
    struct sockaddr_in clnt_adr;
    socklen_t clnt_adr_sz;

    char msg[BUF_SIZE];

    FILE *rfp;
    FILE *wfp;


    if ( argc != 2) {
        printf("Usage: %s <port> \n", argv[0]);
        exit(1);
    }

    serv_sock = socket(PF_INET, SOCK_STREAM, 0);
    if (serv_sock == -1) {
        error_handling("socket() error");
    }

    memset(&serv_adr,0, sizeof(serv_adr));
    serv_adr.sin_family=AF_INET;
    serv_adr.sin_addr.s_addr=htonl(INADDR_ANY);
    serv_adr.sin_port=htons(atoi(argv[1]));

    if (-1 == bind(serv_sock, (struct sockaddr * ) &serv_adr, 
        sizeof(serv_adr) )) {
        error_handling("bind() error");
    }

    if (listen(serv_sock, 5) == -1) {
        error_handling("listen() error");
    }

    clnt_adr_sz = sizeof(clnt_adr);
    
    for (i = 0;i < 5; ++i) {
        clnt_sock=accept(serv_sock, (struct sockaddr *) &clnt_adr, &clnt_adr_sz);
        if (-1 == clnt_sock){
            error_handling("accept() error");
        }
        else {
            printf("Connected client %d \n", i + 1);
        }
        rfp = fdopen(clnt_sock, "r");
        wfp = fdopen(clnt_sock, "w");

        while (!feof(rfp))
        {
            fgets(msg, BUF_SIZE, rfp);
            fputs(msg, rfp);
            fflush(wfp);
        }
        fclose(rfp);
        fclose(wfp);
    }
    close(serv_sock);

    return 0;
}
void error_handling(char *msg)
{
    fputs(msg, stderr);
    fputc('\n', stderr);
    exit(1);
}